Mandrel vs. pressure bends

[ikessky]

Okay, lets start another good debate. Everywhere you read, companies are talking about how much better their mandrel bends are compared to old fashion pressure bends. Now, I understand that that is probably true because the pressure bends decrease the size of the tube at the bend points. Has anyone actually seen any data that shows how much a person can gain in going with mandrel bends? Let's just take a 2.25" mandrel bent system compared to a 2.5" pressure bent system. Which one will yeild a higher flow?

As a side note, I do understand how mandrel bends are made. Can a person who already has a tube bender (pressure bender) simply buy the mandrels that go on the inside of the tube and be able to make mandrel bends?

[Anonymous]

No Mandrel Benders are extremely expensive machines, which explains why the piping is so expensive.

the 2.25" system would flow better with mandrels than a 2.5 would with press bends.

Mine goes from 2.5" mandrel bends, and Y's into dual 2.25" with press bends.

[ikessky]

If you look at this in theory though, all you really need is the mandrel to keep it from decreasing size at the bend points. Am I missing something here?

[RacerX11]

In theory, you also need some mechanism to keep the mandrel in the proper location during the bending process. This is the hard part. It sounds simpler than it is. This is why the equipment is so expensive.

It is sometimes easier and cheaper to just buy the mandrel-bent elbows and have a muffler shop piece-together a complete system for you.

Marty

[ikessky]

The reason I'm asking is because I would like to be able to fab up systems by myself and make a little money on the side doing exhaust work and custom CAI's. Maybe I'll just have to find a source that can sell me cheap bends and then I'll just TIG everything into place.

[RacerX11]

JC Whitney sells both mild and stainless mandrel bends in 90, 45 and 180 degree elbows. They aren't quite as high quality as bends from other manufacturers such as Burns Stainless or Headers by Ed, but they are very reasonably priced. I have used their mild steel bends to fab up my exhaust system, intake piping, and also intercooler piping on turbo cars.

Marty

[geoffinbc]

Mandrel bends eliminate alot more turbulance. Also the smaller diameter you can go the faster the velocity will be. But there is a point where too small will create restriction. And when you go too big the exhaust will have excessive turbulance slow velocity and in the end poor performance. So keep within reason.

[ikessky]

If I can possibly go with mandrel bent, it will be 2.25". If I'm forced to go with pressure bends, it will have to be 2.5". The bend points on that will actually probably be smaller than 2.25" though.

[v6h.o.]

i run a 2.5 inch mandrel bent system i made myself on the bird.

pieced it all together. was a time consuming process but well worth it.

[akira]

An old trick I have seen is to fill the pipe with sand and heat it as you bend it. My dad showed me when I was young. It's not as good as a mandrel bend but for the price.......

[Lyle's GTP]

Maybe consider only having the large bends done by mandrell and press the rest. It's the large bends that collapse the pipe so much.

[ikessky]

I think I'm just going to go with the elbows. They really shouldn't cost me that much and I can get everything mandrel bent.

[Canada]

2.25" Mandrel or 2.5" press....which flows better? Which has more square inches? That depends on how crappy the press bend is. I'd imagine most press bends have a rib greater than 0.25".

Sure, mandrel bends are more costly.





BUT.




If you are truely lookinf for max. performance, you'll go with a mandrel bend. Bar none, it IS better.